In both of those videos, the wobbly/liquid animation of the paths looks simple enough to create by keyframing the path shape and manually deforming the path.
Hi and thanks Todd_Kopriva for your answer,
do you know or someone know where i can find a tutorial to explain how to do this, i'm not really strong (and new) in animation and i would like to know how to do this. It's reaaly great to see
Start here to learn After Effects: http://adobe.ly/bjBT3P
Here's where to start to learn about shape layers and vector graphics in After Effects: